Opinion published: 13 September 2016 doi: 10.3389/fendo.2016.00124
Screening for Obstructive Sleep Apnea in Type 2 Diabetes patients – Questionnaires Are not Good Enough Katerina Westlake1 and Jan Polak1,2* 1 2nd Internal Medicine Department, Vinohrady Teaching Hospital, Prague, Czech Republic, 2 Third Faculty of Medicine, Center for Research on Diabetes, Metabolism and Nutrition, Charles University in Prague, Prague, Czech Republic
Keywords: type 2 diabetes, cardiovascular risk factor, sleep apnea, screening, Berlin questionnaire, STOP Bang questionnaire, home sleep monitor
Edited by: Aaron Vinik, Eastern Virginia Medical School, USA Reviewed by: Rade Vukovic, Mother and Child Health Care Institute of Serbia, Serbia *Correspondence: Jan Polak [email protected] Specialty section: This article was submitted to Diabetes, a section of the journal Frontiers in Endocrinology Received: 27 March 2016 Accepted: 30 August 2016 Published: 13 September 2016 Citation: Westlake K and Polak J (2016) Screening for Obstructive Sleep Apnea in Type 2 Diabetes Patients – Questionnaires Are Not Good Enough. Front. Endocrinol. 7:124. doi: 10.3389/fendo.2016.00124
The shorter life expectancy of patients with type 2 diabetes caused by cardiovascular and cerebrovascular diseases compels clinicians to make a systematic effort to address traditional cardiovascular risk factors, such as dyslipidemia, hypertension, hyperglycemia, obesity, and smoking. However, another major cardiovascular risk factor substantially influencing the quality and length of life – obstructive sleep apnea syndrome (OSA) – is frequently overlooked. OSA is characterized by a repetitive upper airway obstruction during sleep leading to intermittent hypoxemia and sleep fragmentation. Numerous epidemiological studies have proved that untreated OSA represents an independent risk factor significantly increasing all cause as well as cardiovascular, cerebrovascular, and cancer mortality (1–7). The importance of OSA is underscored by its considerable prevalence ranging from 5 to 10% in the general population and is even higher in the population of type 2 diabetes patients where a prevalence of ~70% was reported (8–10). Furthermore, ~90% of all subjects suffering from moderate or severe OSA remain undiagnosed (11). Acknowledging the clinical significance of untreated OSA, the American Diabetes Association’s Standards of Care recommend the active treatment of OSA when diagnosed (12), while the International Diabetes Federation’s guidelines emphasize the need for systematic OSA screening in all patients with type 2 diabetes (13). The suggested screening approach is split into two steps. In step one, patients fill in a questionnaire stratifying respondents into high or low risk of having OSA. Subsequently, in step two, high-risk patients undergo home sleep monitoring consisting of overnight registration of pulse oxymetry, preferably combined with nasal flow measurement and other accessory signals. Although such a two-step approach seems intuitively attractive, it should be noted that there are currently no studies supporting this approach or validating any of the available questionnaires in a population of type 2 diabetes patients. In fact, the recommendation suggesting a two-step OSA screening procedure is not based on any scientific evidence. Since the performance characteristics of screening questionnaires substantially influence the outcome of the whole screening procedure, this article scrutinizes the key features of available questionnaires and their performance. Subsequently, we will discuss the clinical and ethical impact of OSA questionnaire screening in populations with high cardiovascular risk such as patients with type 2 diabetes. The overarching goal of this article is to advocate OSA screening in type 2 diabetes patients using simple home sleep monitoring devices instead of inaccurate and therefore potentially dangerous questionnaires. Screening questionnaires were introduced to improve the recognition of patients suffering from moderate or severe OSA (indicated for treatment), particularly in primary care practice, where such patients remained largely unrecognized without systematic screening. The various questionnaires deployed for screening summarize and quantify the presence of risk factors that are strongly associated with OSA – namely, obesity, large neck circumference, hypertension, snoring, and
Frontiers in Endocrinology | www.frontiersin.org
1
September 2016 | Volume 7 | Article 124
Westlake and Polak
OSA Screening in T2D Patients
different symptoms of daytime tiredness/sleepiness. However, it has proved to be a considerable challenge to create a questionnaire that would be both (1) sensitive enough to minimize the chance of marking patients falsely as being at low risk of OSA and therefore inadvertently denying them appropriate treatment and (2) specific enough to minimize the chance of inappropriately marking healthy patients as being at high risk of OSA and leading them to the unnecessary use of medical resources. One of the first questionnaires to be developed and which remains widely used is the Berlin questionnaire, an outcome of the 1966 Berlin Conference on Sleep in Primary Care. The usefulness of the Berlin questionnaire as a tool to recognize patients with OSA was consequently validated in a study comparing the performance of the Berlin questionnaire with polysomnography (which is the gold standard for the diagnosis of OSA). The sensitivity and specificity of the Berlin questionnaire to identify moderate or severe OSA (i.e., a level of severity where treatment is recommended) were found to be 0.54 and 0.97, respectively (14). Soon after publication, these results were challenged by other clinicians, who recalculated the published data and found a sensitivity of 0.95 and specificity of 0.48 (15). Nevertheless, the major limitation of the study resides in the fact that the high-risk subjects identified by the Berlin questionnaire were over-represented in the polysomnography subgroup (69% highrisk subjects, while there were only 38% high-risk subjects in the whole study population). The limited number of low-risk subjects as identified by the Berlin questionnaire that were recruited into the polysomnography group (31 subjects) also resulted in a low number (exactly one patient) of subjects with polysomnographically verified severe OSA and nobody with moderate OSA. Clearly, the insufficient sample size of the study makes sensitivity and specificity calculations unreliable. Consequently, several studies retested the performance of the Berlin questionnaire in various countries and in different patient populations (primary care patients, preoperative patients, patients referred for suspected OSA, or sleep clinic patients), and they reported conflicting results with sensitivity and specificity ranging from 0.43 to 0.89 and 0.33 to 0.79, respectively (16–19). In summary, the Berlin questionnaire improves the identification of patients with OSA; however, its performance seems to be variable and uncertain in studied populations. In 2006, the STOP and its upgraded version, the STOP Bang questionnaires, were introduced and applied in preoperative patients (20). Both questionnaires score one point for the presence of some of the symptoms such as snoring, tiredness, observed pauses in breathing, high blood pressure, BMI, age, neck circumference, and gender. The initial performance characteristics of the STOP Bang questionnaire validated on 177 preoperative patients were promising, finding sensitivity 0.92, and specificity 0.43 to detect moderate or severe OSA (using a total questionnaire scoring of ≥5). With continued recruitment and an increased number of assessed subjects to 746, sensitivity dropped to 0.23 and specificity increased to 0.56. In an effort to increase the questionnaire sensitivity, it was suggested to lower the score threshold indicative of being at high risk of having OSA to 3 points, which helped to increase sensitivity to 0.68 but at the cost of specificity, dropping to 0.11 (21). Furthermore, no study to
Frontiers in Endocrinology | www.frontiersin.org
date evaluated the questionnaire separately for men and women even though gender plays a major role in the outcome of scoring. The key advantage of the STOP and STOP Bang questionnaires is their straightforward application and interpretation. However, their performance characteristics are too limited to justify their use as a screening tool for such a serious condition in a population that is already affected by a high incidence of cardiovascular events. A number of other questionnaires were also developed and used to screen subjects for OSA, e.g., Epworth’s Sleepiness Scale, the ASA Checklist, the Sleep Apnea of Sleep Disorders Questionnaire, the Wisconsin Questionnaire, or the FourVariable Screening Tool. Although some of them performed better than others, none of them was convincing enough to become widely adopted in practice. The inherent limitation of any OSA screening questionnaire is that some of the answers are often based on the patient’s judgment and self-perception. For example, when asked about snoring, patients typically rely on the information from their bed partners. However, patients sleeping in separate bedrooms or living alone might not be able to answer appropriately. Similarly, tiredness/sleepiness is frequently perceived as a natural symptom of aging or attributed to other chronic diseases. It should be emphasized that a false negative result from an OSA screening questionnaire might have serious clinical, ethical, and forensic connotations for a type 2 diabetes patient (therefore in elevated cardiovascular risk) who is suffering from moderate or severe OSA but who is deprived of therapy if inappropriately marked as being at low risk. In contrast to questionnaires, technological advancements in recent years have opened new possibilities for accurate OSA screening in the form of various home sleep monitoring devices (typically recording breathing and hemoglobin saturation). These devices were shown to have an acceptably high sensitivity and specificity ~0.90 (22–24). The overall complexity of using home sleep monitoring devices is similar to a routinely performed 24-h ECG or a blood pressure monitoring device. The growing availability and affordability of home sleep monitoring devices raises the fundamental question if it is sensible and clinically acceptable to use questionnaires as the first screening step. In answer to this, clinicians should examine the evidence keeping in mind the best interests of the patient. Our analysis found that due to the low sensitivity of questionnaires, questionnaire-based OSA screening fails to identify up to 57% of patients with moderate or severe OSA (who should receive treatment) while reassuring them that they are at low risk of OSA. Support for proceeding directly to OSA screening using only home sleep monitoring without prior stratification by questionnaire into high- and low-risk groups is strengthened by the fact that a substantial number of subjects (in our experience about 50% of patients with type 2 diabetes) are identified as high risk by questionnaires and anyway subsequently undergo home sleep monitoring as a second step in the current two-step OSA screening approach. To conclude, the vast majority of patients with OSA are not aware of any illness and they remain undiagnosed. However, OSA is an important cardiovascular risk factor highly prevalent in type 2 diabetes patients. Between 25 and 30% of patients with type 2 2
September 2016 | Volume 7 | Article 124
Westlake and Polak
OSA Screening in T2D Patients
diabetes who are already at high cardiovascular risk because of diabetes also suffer from moderate or severe OSA and should be treated as the treatment reduces mortality to the control group level. Therefore, physicians should improve the detection of OSA ideally via a systematic, precise, and reliable screening program. In our view, the recommended optimal OSA screening procedure should be evidence-based and reflect technological advancements in the field of sleep medicine. Questionnaire-based screening for OSA in the type 2 diabetes population is not supported by scientific evidence and might have a consequence as discussed above. Therefore, we advocate using home sleep monitoring devices as the first and only screening tool in all patients with type 2 diabetes as they provide an objective OSA assessment with proven high sensitivity and specificity to a level that approaches the gold standard polysomnography diagnosis. Moreover, they are easy to use by both patients and medical care professionals. Nevertheless,
screening questionnaires still represent a useful tool for OSA screening in the general population where the prevalence of OSA is much lower compared to type 2 diabetes population and where the clinical consequences of a false negative finding are not so detrimental due to the overall lower cardiovascular risk profile.
AUTHOR CONTRIBUTIONS JP and KW participated in the data collection and manuscript preparation.
FUNDING This work was funded by the grant from the Czech Science Foundation GACR 13-27735S and by the Grant of the Czech Ministry of Health AZV 15-30155A.
REFERENCES
14. Netzer NC, Stoohs RA, Netzer CM, Clark K, Strohl KP. Using the Berlin questionnaire to identify patients at risk for the sleep apnea syndrome. Ann Intern Med (1999) 131:485–91. 15. Strauss RS, Browner WS. Risk for obstructive sleep apnea. Ann Intern Med (2000) 132:758–9. doi:10.7326/0003-4819-132-9-200005020-00013 16. Hrubos-Strøm H, Randby A, Namtvedt SK, Kristiansen HA, Einvik G, Benth J, et al. A Norwegian population-based study on the risk and prevalence of obstructive sleep apnea. The Akershus Sleep Apnea Project (ASAP). J Sleep Res (2011) 20:162–70. doi:10.1111/j.1365-2869.2010.00861.x 17. Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan S, Islam S, et al. Validation of the Berlin questionnaire and American Society of Anesthesiologists checklist as screening tools for obstructive sleep apnea in surgical patients. Anesthesiology (2008) 108:822–30. doi:10.1097/ ALN.0b013e31816d91b5 18. Karakoc O, Akcam T, Genc H, Yetkin S, Piskin B, Gerek M. Use of the Berlin questionnaire to screen at-risk patients for obstructive sleep apnea. B-ENT (2014) 10:21–5. 19. Pataka A, Daskalopoulou E, Kalamaras G, Fekete Passa K, Argyropoulou P. Evaluation of five different questionnaires for assessing sleep apnea syndrome in a sleep clinic. Sleep Med (2014) 15:776–81. doi:10.1016/j.sleep.2014.03.012 20. Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan S, Islam S, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology (2008) 108:812–21. doi:10.1097/ALN.0b013e31816d83e4 21. Chung F, Subramanyam R, Liao P, Sasaki E, Shapiro C, Sun Y. High STOP-Bang score indicates a high probability of obstructive sleep apnoea. Br J Anaesth (2012) 108:768–75. doi:10.1093/bja/aes022 22. Erman MK, Stewart D, Einhorn D, Gordon N, Casal E. Validation of the ApneaLinkTM for the screening of sleep apnea: a novel and simple singlechannel recording device. J Clin Sleep Med (2007) 3:387–92. 23. Chen H, Lowe AA, Bai Y, Hamilton P, Fleetham JA, Almeida FR. Evaluation of a portable recording device (ApneaLinkTM) for case selection of obstructive sleep apnea. Sleep Breath (2009) 13:213–9. doi:10.1007/s11325-008-0232-4 24. Nigro CA, Serrano F, Aimaretti S, Gonzalez S, Codinardo C, Rhodius E. Utility of ApneaLink for the diagnosis of sleep apnea-hypopnea syndrome. Medicina (B Aires) (2010) 70:53–9.
1. Young T, Finn L, Peppard PE, Szklo-Coxe M, Austin D, Nieto FJ, et al. Sleep disordered breathing and mortality: eighteen-year follow-up of the Wisconsin sleep cohort. Sleep (2008) 31:1071–8. doi:10.1016/S8756-3452(08) 79181-3 2. Punjabi NM, Caffo BS, Goodwin JL, Gottlieb DJ, Newman AB, O’Connor GT, et al. Sleep-disordered breathing and mortality: a prospective cohort study. PLoS Med (2009) 6:e1000132. doi:10.1371/journal.pmed.1000132 3. Dong J-Y, Zhang Y-H, Qin L-Q. Obstructive sleep apnea and cardiovascular risk: meta-analysis of prospective cohort studies. Atherosclerosis (2013) 229:489–95. doi:10.1016/j.atherosclerosis.2013.04.026 4. Marin JM, Carrizo SJ, Vicente E, Agusti AG. Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study. Lancet (2005) 365:1046–53. doi:10.1016/S0140-6736(05)74229-X 5. Anandam A, Patil M, Akinnusi M, Jaoude P, El-Solh AA. Cardiovascular mortality in obstructive sleep apnoea treated with continuous positive airway pressure or oral appliance: an observational study. Respirology (2013) 18:1184–90. doi:10.1111/resp.12140 6. Martínez-García M-A, Campos-Rodríguez F, Catalán-Serra P, SolerCataluña J-J, Almeida-Gonzalez C, De la Cruz Morón I, et al. Cardiovas cular mortality in obstructive sleep apnea in the elderly: role of long-term continuous positive airway pressure treatment: a prospective observational study. Am J Respir Crit Care Med (2012) 186:909–16. doi:10.1164/rccm. 201203-0448OC 7. Jennum P, Tønnesen P, Ibsen R, Kjellberg J. All-cause mortality from obstructive sleep apnea in male and female patients with and without continuous positive airway pressure treatment: a registry study with 10 years of follow-up. Nat Sci Sleep (2015) 7:43–50. doi:10.2147/NSS.S75166 8. Resnick HE, Redline S, Shahar E, Gilpin A, Newman A, Walter R, et al. Diabetes and sleep disturbances: findings from the Sleep Heart Health Study. Diabetes Care (2003) 26:702–9. doi:10.2337/diacare.26.3.702 9. Laaban J-P, Daenen S, Léger D, Pascal S, Bayon V, Slama G, et al. Prevalence and predictive factors of sleep apnoea syndrome in type 2 diabetic patients. Diabetes Metab (2009) 35:372–7. doi:10.1016/j.diabet.2009.03.007 10. Aronsohn RS, Whitmore H, Van Cauter E, Tasali E. Impact of untreated obstructive sleep apnea on glucose control in type 2 diabetes. Am J Respir Crit Care Med (2010) 181:507–13. doi:10.1164/rccm.200909-1423OC 11. Young T, Evans L, Finn L, Palta M. Estimation of the clinically diagnosed proportion of sleep apnea syndrome in middle-aged men and women. Sleep (1997) 20:705–6. 12. American Diabetes Association. Standards of medical care in diabetes – 2014. Diabetes Care (2014) 37:S14–80. doi:10.2337/dc14-S014 13. Federation ID. The IDF Consensus Statement on Sleep Apnoea and Type 2 Diabetes. Brussels: International Diabetes Federation (2008).
Frontiers in Endocrinology | www.frontiersin.org
Conflict of Interest Statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Copyright © 2016 Westlake and Polak. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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September 2016 | Volume 7 | Article 124
Screening for Obstructive Sleep Apnea in Type 2 Diabetes patients – Questionnaires Are not Good Enough Katerina Westlake1 and Jan Polak1,2* 1 2nd Internal Medicine Department, Vinohrady Teaching Hospital, Prague, Czech Republic, 2 Third Faculty of Medicine, Center for Research on Diabetes, Metabolism and Nutrition, Charles University in Prague, Prague, Czech Republic
Keywords: type 2 diabetes, cardiovascular risk factor, sleep apnea, screening, Berlin questionnaire, STOP Bang questionnaire, home sleep monitor
Edited by: Aaron Vinik, Eastern Virginia Medical School, USA Reviewed by: Rade Vukovic, Mother and Child Health Care Institute of Serbia, Serbia *Correspondence: Jan Polak [email protected] Specialty section: This article was submitted to Diabetes, a section of the journal Frontiers in Endocrinology Received: 27 March 2016 Accepted: 30 August 2016 Published: 13 September 2016 Citation: Westlake K and Polak J (2016) Screening for Obstructive Sleep Apnea in Type 2 Diabetes Patients – Questionnaires Are Not Good Enough. Front. Endocrinol. 7:124. doi: 10.3389/fendo.2016.00124
The shorter life expectancy of patients with type 2 diabetes caused by cardiovascular and cerebrovascular diseases compels clinicians to make a systematic effort to address traditional cardiovascular risk factors, such as dyslipidemia, hypertension, hyperglycemia, obesity, and smoking. However, another major cardiovascular risk factor substantially influencing the quality and length of life – obstructive sleep apnea syndrome (OSA) – is frequently overlooked. OSA is characterized by a repetitive upper airway obstruction during sleep leading to intermittent hypoxemia and sleep fragmentation. Numerous epidemiological studies have proved that untreated OSA represents an independent risk factor significantly increasing all cause as well as cardiovascular, cerebrovascular, and cancer mortality (1–7). The importance of OSA is underscored by its considerable prevalence ranging from 5 to 10% in the general population and is even higher in the population of type 2 diabetes patients where a prevalence of ~70% was reported (8–10). Furthermore, ~90% of all subjects suffering from moderate or severe OSA remain undiagnosed (11). Acknowledging the clinical significance of untreated OSA, the American Diabetes Association’s Standards of Care recommend the active treatment of OSA when diagnosed (12), while the International Diabetes Federation’s guidelines emphasize the need for systematic OSA screening in all patients with type 2 diabetes (13). The suggested screening approach is split into two steps. In step one, patients fill in a questionnaire stratifying respondents into high or low risk of having OSA. Subsequently, in step two, high-risk patients undergo home sleep monitoring consisting of overnight registration of pulse oxymetry, preferably combined with nasal flow measurement and other accessory signals. Although such a two-step approach seems intuitively attractive, it should be noted that there are currently no studies supporting this approach or validating any of the available questionnaires in a population of type 2 diabetes patients. In fact, the recommendation suggesting a two-step OSA screening procedure is not based on any scientific evidence. Since the performance characteristics of screening questionnaires substantially influence the outcome of the whole screening procedure, this article scrutinizes the key features of available questionnaires and their performance. Subsequently, we will discuss the clinical and ethical impact of OSA questionnaire screening in populations with high cardiovascular risk such as patients with type 2 diabetes. The overarching goal of this article is to advocate OSA screening in type 2 diabetes patients using simple home sleep monitoring devices instead of inaccurate and therefore potentially dangerous questionnaires. Screening questionnaires were introduced to improve the recognition of patients suffering from moderate or severe OSA (indicated for treatment), particularly in primary care practice, where such patients remained largely unrecognized without systematic screening. The various questionnaires deployed for screening summarize and quantify the presence of risk factors that are strongly associated with OSA – namely, obesity, large neck circumference, hypertension, snoring, and
Frontiers in Endocrinology | www.frontiersin.org
1
September 2016 | Volume 7 | Article 124
Westlake and Polak
OSA Screening in T2D Patients
different symptoms of daytime tiredness/sleepiness. However, it has proved to be a considerable challenge to create a questionnaire that would be both (1) sensitive enough to minimize the chance of marking patients falsely as being at low risk of OSA and therefore inadvertently denying them appropriate treatment and (2) specific enough to minimize the chance of inappropriately marking healthy patients as being at high risk of OSA and leading them to the unnecessary use of medical resources. One of the first questionnaires to be developed and which remains widely used is the Berlin questionnaire, an outcome of the 1966 Berlin Conference on Sleep in Primary Care. The usefulness of the Berlin questionnaire as a tool to recognize patients with OSA was consequently validated in a study comparing the performance of the Berlin questionnaire with polysomnography (which is the gold standard for the diagnosis of OSA). The sensitivity and specificity of the Berlin questionnaire to identify moderate or severe OSA (i.e., a level of severity where treatment is recommended) were found to be 0.54 and 0.97, respectively (14). Soon after publication, these results were challenged by other clinicians, who recalculated the published data and found a sensitivity of 0.95 and specificity of 0.48 (15). Nevertheless, the major limitation of the study resides in the fact that the high-risk subjects identified by the Berlin questionnaire were over-represented in the polysomnography subgroup (69% highrisk subjects, while there were only 38% high-risk subjects in the whole study population). The limited number of low-risk subjects as identified by the Berlin questionnaire that were recruited into the polysomnography group (31 subjects) also resulted in a low number (exactly one patient) of subjects with polysomnographically verified severe OSA and nobody with moderate OSA. Clearly, the insufficient sample size of the study makes sensitivity and specificity calculations unreliable. Consequently, several studies retested the performance of the Berlin questionnaire in various countries and in different patient populations (primary care patients, preoperative patients, patients referred for suspected OSA, or sleep clinic patients), and they reported conflicting results with sensitivity and specificity ranging from 0.43 to 0.89 and 0.33 to 0.79, respectively (16–19). In summary, the Berlin questionnaire improves the identification of patients with OSA; however, its performance seems to be variable and uncertain in studied populations. In 2006, the STOP and its upgraded version, the STOP Bang questionnaires, were introduced and applied in preoperative patients (20). Both questionnaires score one point for the presence of some of the symptoms such as snoring, tiredness, observed pauses in breathing, high blood pressure, BMI, age, neck circumference, and gender. The initial performance characteristics of the STOP Bang questionnaire validated on 177 preoperative patients were promising, finding sensitivity 0.92, and specificity 0.43 to detect moderate or severe OSA (using a total questionnaire scoring of ≥5). With continued recruitment and an increased number of assessed subjects to 746, sensitivity dropped to 0.23 and specificity increased to 0.56. In an effort to increase the questionnaire sensitivity, it was suggested to lower the score threshold indicative of being at high risk of having OSA to 3 points, which helped to increase sensitivity to 0.68 but at the cost of specificity, dropping to 0.11 (21). Furthermore, no study to
Frontiers in Endocrinology | www.frontiersin.org
date evaluated the questionnaire separately for men and women even though gender plays a major role in the outcome of scoring. The key advantage of the STOP and STOP Bang questionnaires is their straightforward application and interpretation. However, their performance characteristics are too limited to justify their use as a screening tool for such a serious condition in a population that is already affected by a high incidence of cardiovascular events. A number of other questionnaires were also developed and used to screen subjects for OSA, e.g., Epworth’s Sleepiness Scale, the ASA Checklist, the Sleep Apnea of Sleep Disorders Questionnaire, the Wisconsin Questionnaire, or the FourVariable Screening Tool. Although some of them performed better than others, none of them was convincing enough to become widely adopted in practice. The inherent limitation of any OSA screening questionnaire is that some of the answers are often based on the patient’s judgment and self-perception. For example, when asked about snoring, patients typically rely on the information from their bed partners. However, patients sleeping in separate bedrooms or living alone might not be able to answer appropriately. Similarly, tiredness/sleepiness is frequently perceived as a natural symptom of aging or attributed to other chronic diseases. It should be emphasized that a false negative result from an OSA screening questionnaire might have serious clinical, ethical, and forensic connotations for a type 2 diabetes patient (therefore in elevated cardiovascular risk) who is suffering from moderate or severe OSA but who is deprived of therapy if inappropriately marked as being at low risk. In contrast to questionnaires, technological advancements in recent years have opened new possibilities for accurate OSA screening in the form of various home sleep monitoring devices (typically recording breathing and hemoglobin saturation). These devices were shown to have an acceptably high sensitivity and specificity ~0.90 (22–24). The overall complexity of using home sleep monitoring devices is similar to a routinely performed 24-h ECG or a blood pressure monitoring device. The growing availability and affordability of home sleep monitoring devices raises the fundamental question if it is sensible and clinically acceptable to use questionnaires as the first screening step. In answer to this, clinicians should examine the evidence keeping in mind the best interests of the patient. Our analysis found that due to the low sensitivity of questionnaires, questionnaire-based OSA screening fails to identify up to 57% of patients with moderate or severe OSA (who should receive treatment) while reassuring them that they are at low risk of OSA. Support for proceeding directly to OSA screening using only home sleep monitoring without prior stratification by questionnaire into high- and low-risk groups is strengthened by the fact that a substantial number of subjects (in our experience about 50% of patients with type 2 diabetes) are identified as high risk by questionnaires and anyway subsequently undergo home sleep monitoring as a second step in the current two-step OSA screening approach. To conclude, the vast majority of patients with OSA are not aware of any illness and they remain undiagnosed. However, OSA is an important cardiovascular risk factor highly prevalent in type 2 diabetes patients. Between 25 and 30% of patients with type 2 2
September 2016 | Volume 7 | Article 124
Westlake and Polak
OSA Screening in T2D Patients
diabetes who are already at high cardiovascular risk because of diabetes also suffer from moderate or severe OSA and should be treated as the treatment reduces mortality to the control group level. Therefore, physicians should improve the detection of OSA ideally via a systematic, precise, and reliable screening program. In our view, the recommended optimal OSA screening procedure should be evidence-based and reflect technological advancements in the field of sleep medicine. Questionnaire-based screening for OSA in the type 2 diabetes population is not supported by scientific evidence and might have a consequence as discussed above. Therefore, we advocate using home sleep monitoring devices as the first and only screening tool in all patients with type 2 diabetes as they provide an objective OSA assessment with proven high sensitivity and specificity to a level that approaches the gold standard polysomnography diagnosis. Moreover, they are easy to use by both patients and medical care professionals. Nevertheless,
screening questionnaires still represent a useful tool for OSA screening in the general population where the prevalence of OSA is much lower compared to type 2 diabetes population and where the clinical consequences of a false negative finding are not so detrimental due to the overall lower cardiovascular risk profile.
AUTHOR CONTRIBUTIONS JP and KW participated in the data collection and manuscript preparation.
FUNDING This work was funded by the grant from the Czech Science Foundation GACR 13-27735S and by the Grant of the Czech Ministry of Health AZV 15-30155A.
REFERENCES
14. Netzer NC, Stoohs RA, Netzer CM, Clark K, Strohl KP. Using the Berlin questionnaire to identify patients at risk for the sleep apnea syndrome. Ann Intern Med (1999) 131:485–91. 15. Strauss RS, Browner WS. Risk for obstructive sleep apnea. Ann Intern Med (2000) 132:758–9. doi:10.7326/0003-4819-132-9-200005020-00013 16. Hrubos-Strøm H, Randby A, Namtvedt SK, Kristiansen HA, Einvik G, Benth J, et al. A Norwegian population-based study on the risk and prevalence of obstructive sleep apnea. The Akershus Sleep Apnea Project (ASAP). J Sleep Res (2011) 20:162–70. doi:10.1111/j.1365-2869.2010.00861.x 17. Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan S, Islam S, et al. Validation of the Berlin questionnaire and American Society of Anesthesiologists checklist as screening tools for obstructive sleep apnea in surgical patients. Anesthesiology (2008) 108:822–30. doi:10.1097/ ALN.0b013e31816d91b5 18. Karakoc O, Akcam T, Genc H, Yetkin S, Piskin B, Gerek M. Use of the Berlin questionnaire to screen at-risk patients for obstructive sleep apnea. B-ENT (2014) 10:21–5. 19. Pataka A, Daskalopoulou E, Kalamaras G, Fekete Passa K, Argyropoulou P. Evaluation of five different questionnaires for assessing sleep apnea syndrome in a sleep clinic. Sleep Med (2014) 15:776–81. doi:10.1016/j.sleep.2014.03.012 20. Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan S, Islam S, et al. STOP questionnaire: a tool to screen patients for obstructive sleep apnea. Anesthesiology (2008) 108:812–21. doi:10.1097/ALN.0b013e31816d83e4 21. Chung F, Subramanyam R, Liao P, Sasaki E, Shapiro C, Sun Y. High STOP-Bang score indicates a high probability of obstructive sleep apnoea. Br J Anaesth (2012) 108:768–75. doi:10.1093/bja/aes022 22. Erman MK, Stewart D, Einhorn D, Gordon N, Casal E. Validation of the ApneaLinkTM for the screening of sleep apnea: a novel and simple singlechannel recording device. J Clin Sleep Med (2007) 3:387–92. 23. Chen H, Lowe AA, Bai Y, Hamilton P, Fleetham JA, Almeida FR. Evaluation of a portable recording device (ApneaLinkTM) for case selection of obstructive sleep apnea. Sleep Breath (2009) 13:213–9. doi:10.1007/s11325-008-0232-4 24. Nigro CA, Serrano F, Aimaretti S, Gonzalez S, Codinardo C, Rhodius E. Utility of ApneaLink for the diagnosis of sleep apnea-hypopnea syndrome. Medicina (B Aires) (2010) 70:53–9.
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Conflict of Interest Statement: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Copyright © 2016 Westlake and Polak. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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September 2016 | Volume 7 | Article 124
